With the continuous development of distributed solar, wind power and other renewable energy sources, renewable energy sources which has its own features, such as intermittent and randomness volatility, brings great challenges to the stable operation of power grid. Aiming at meeting the requirement of balancing the fluctuating renewable energy sources of micro grid, this paper proposes the operating control strategies of the zinc bromine flow battery storage. Firstly, the equivalent mathematical model based on the working principle of the zinc bromine flow battery is established; Secondly, a dual closed-loop strategy for the DC/DC converter is proposed, of which the inner loop is peak current control on zinc bromine flow battery side inductance while the outer loop is a switch control by constant active power and trickle current. By resorting the DC/AC grid side converter, the stability of DC bus voltage is maintained; Then, this paper proposes the optimization power control strategies of zinc bromine battery energy storage system as a constraint of state of charge and DC bus voltage; Finally, a 50kW zinc bromine flow battery energy storage system test platform is built, and the charging and discharging characteristics of zinc bromine energy storage system (ZESS) is researched in grid-connected mode, the test results have shown that the proposed power optimization control strategies for zinc bromine energy storage system could smooth renewable energy sources power fluctuation.